Poster of the Aleutian Islands, Alaska Earthquake of 30 August 2013 - Magnitude 7.0

Tectonic Summary

The August 30, 2013 M 7.0 earthquake southeast of Adak, Alaska, occurred as the result of thrust faulting on or near the subduction zone interface between the Pacific and North America plates. At the location of this event, the Pacific plate moves towards the northwest with respect to North America at a rate of approximately 73 mm/yr, beginning its descent into the mantle at the Aleutian trench approximately 130 km south of the August 30 earthquake. The depth and mechanism of this earthquake are consistent with it occurring along the megathrust interface between these two plates. The Aleutians Arc is familiar with large earthquakes -two-dozen events of M 6.5 or larger have occurred over the last century within 250 km of the August 30 earthquake. The largest of these was an Mw 8.6 earthquake in March of 1957, whose hypocenter was located just 15 km south of the August 30 earthquake. Aftershocks associated with the 1957 event extended for more than 1000 km along the arc, roughly from the International Dateline in the west to Unimak Island in the east. The 1957 earthquake also resulted in a large tsunami that was observed throughout the Pacific Basin, and caused damage locally along the Aleutian Arc and in Hawaii. Other large nearby events include the May 1986 Mw 8.0 earthquake 40 km to the southeast, and the June 1996 Mw 7.9 earthquake 150 km to the west. Neither of these more recent events are known to have caused fatalities or significant damage.

Earthquake Report

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